The internet is full of useful and fun DIY projects that you can do with just a few items from around your house. Having a trip-wire alarm would be great for when you are out camping or maybe just those times you need a warning if someone is coming your way. Regardless of what you plan on using it for, all you will need to create this little battery operated trip-wire alarm is a AA battery, some metal push pins, some wires and a string. The video below will take you into more detail of how to set everything up
This trip-wire alarm works by completing a circuit when the string is pulled away. In the video, once the circuit is completed it sets fire to a flammable substance. If you don’t have anything like that laying around, you could just wire up an LED, or maybe even hook up a buzzer circuit. If you really want to scare that intruder away, hook up the fuze to a bunch of firecrackers and they will go running.
The youtube behind this project does a lot of DIY videos about mini tools like this, and it is surprising how much you can make with just a little bit of ingenuity. He makes a tiny Dremel from an old motor along with tons of other stuff. Given a day and a drawer full of junk, you could probably make everything and have yourself a bunch of nifty little tools.